Translation of abstract (English)

Nepal is among the countries where landslides top the list of the natural hazards. The present study, which has an earth sciences approach, will point out the important role of landslides for the mountain farming population and for the character of the landscape in the Nepalese Himalayas and, in particular, in the study area. The study also takes into account, however, the socioeconomic effects of the landslides as well as the ecological aspects and the current geographic development research. This is discussed in detail using the example of the Sikha Valley, a branch valley to the east of the upper Kali Gandaki Valley, in the mountain country of Central Nepal in the southwestern Annapurna Massif. A differentiated view of landslides is presented, in which landslides are regarded as an integral part of the cultural landscape, the investigations having shown that slide areas neither constitute a total loss for agriculture nor are they simply waste land, rather they can be utilized in many different ways. With its elevation of between 817 and 4,703 m the area ranges from a subtropical-type rice land to the alpine zone. The data basis for this study consists of the results of the author's own fieldwork (1997-99) as well as a comparison of the aerial photographs, statistical data on population development, land use and on the climate as well as numerous interviews. The study focuses on an extensive evaluation of the landslides as the dominant environmental factor and the analysis of the changes in the natural framework conditions taking place as the result of human activity. Even if it is not always possible to differentiate exactly between natural and anthropogenic causes of landslides, it became clear that the natural causes in the study area by far predominate. The study also recorded trends in agricultural development as perceived by the farmers. The high density of a comparatively affluent mountain farming population (particularly Magars) is an indication that the occurrence of numerous landslides is not automatically a crisis situation. The study shows that there are also positive consequences of landslides, they should not be neglected. It was the flattening of the topography caused by fossil landslides that made settlement and agricultural utilization in the study area possible in the first place. The fact that extensive landslide areas, even those which are presently active, are stocked with Alnus nepalensis woods, which supply large quantities of fuelwood and construction timber, lessens the pressure on the more valuable high altitude forests. Landslide areas can also be used as grazing areas and supply stone suitable for use as building material. Thanks to its good water-storing properties, landslide material that has come to rest forms the best soils for, among other things, rice farming (favorable edaphic locations). The period of about 20 years covered by the investigations makes it possible to incorporate the temporal dimension. According to this, the landslide activity in the Sikha Valley has not increased notably in recent decades. The situation now appears even better than, for instance, in the first half of the 1980s. Since then, most larger landslides have at least in part, become overgrown with vegetation. Nowadays predominate low-magnitude / high-frequency land-slide events.